1. Field of the Invention
The present invention relates to a lens barrel where a photographic optical system is disposed movably in an optical axis direction, its driving method, and an image pickup device, such as a digital camera which is equipped with the above-mentioned lens barrel.
2. Description of the Related Art
Conventionally, in a camera equipped with a telescopic lens barrel, the lens barrel is made short in an optical axis direction by being collapsed so as to increase its portability at the time of not shooting, and at the time of shooting, conversely, the lens barrel is projected from a camera body to secure the total length of a shooting lens. In a lens barrel which performs such a telescopic operation, there is known a technology of driving a shooting lens in the lens barrel using a cylindrical lens barrel driving member (hereinafter, referred to as “the drive ring”) which is rotated around a shooting optical axis by a driving force of a motor.
Then, out of the lens barrels using the drive ring, some lens barrels may drive members other than the shooting lens with the drive ring (see Japanese Laid-Open Patent Publication (Kokai) No. 08-122858).
The drive ring in Japanese Laid-Open Patent Publication (Kokai) No. 08-122858 is so constructed as to have, on its outer peripheral surface, a cam for driving a finder lens, and have a shooting lens thereinside. Then, the drive ring rotates around an optical axis of the shooting lens, and drives a finder lens while transferring its driving force to the shooting lens disposed thereinside.
In Japanese Laid-Open Patent Publication (Kokai) No. 09-105982, the drive ring has, at its outer peripheral surface, a convex portion for making a strobe retractable, and this drive ring rotates around an optical axis of a shooting lens, and drives the strobe while transferring its driving force to the shooting lens disposed thereinside.
However, in the above-mentioned conventional cameras, in order to satisfy user needs of using a lens with higher magnification than ever before, there has been desired a lens barrel which can further increase the total length of the lens barrel in a shooting state even in a case where the collapsed lens barrel length is short.
Although it is considered to use the above-mentioned drive ring in order to attain this technology with a simple construction, each of the drive rings used for the conventional lens barrels mentioned above merely functions as means for transferring its driving force to the lens barrel etc. in a telescopic operation, and hence, it is not so constructed that the drive ring itself moves in the optical axis direction. Therefore, the drive ring itself has not been used so as to further increase the total length of the lens barrel in the shooting state.